This invention relates to respirators in general and, more particularly, to a Y-fitting in the patient system of respirators, in which a membrane humidifier is mounted within a housing. The membrane humidifier includes an exchangeable element and a plurality of hollow filaments for the passage of breathing air therethrough and means for externally charging the filaments with water circulating therearound.
A patient is connected to a respirator by means of an inspiration line and an expiration line. In a Y-fitting, the inspiration line through which the breathing gas is supplied is split up into a first branch leading to the patient, and a second branch leading, through a control valve, to the exhaling valve or, in a circulatory respirator, back to the circuit. With the control valve closed, the entire amount of breathing air flows through the first branch to the patient. With the control valve open, the breathing gas stream is deflected in the Y-fitting and, admixed to the air which is exhaled by the patient through the first branch, flows to the exhaling valve or returns to the circuit. By opening and closing the control valve, the breathing phases, the respiratory frequency and the ratio of inhalation to exhalation periods are controlled. Thus, the Y-fitting is an essential, indispensible component part of systems conducting breathing air.
In order to provide for the physical comfort of a patient, a satisfactory relative humidity of the breathing air is needed. A humidity level which is too low would dry up the respiratory tract. Therefore, breathing gas systems contain air dampeners or humidifiers.
Known humidifiers comprise a bundle of hollow filaments through which the breathing gas is directed. The filaments extend in axially parallel arrangement within a casing interposed in the system and provided with connections. The walls of the hollow filaments are impervious to water, but permeable to water vapor. At their front sides, the filaments are firmly connected to each other and to the inside of the casing by a sealing compound. Parallel to and within the bundle of filaments, a perforated tube for circulating water is also secured by the sealing compound. The supplied water flows around the hollow filaments and water vapor penetrates through the filament walls to their interior, thereby, humidifying the breathing air flowing therethrough. The provision of a humidifier in the breathing air supply way, particularly close to the patient as needed, results in a bulky arrangement (West German Pat. No. 26 17 985).
In another known humidifier, also designed with a bundle of hollow filaments inserted between the inspiration tube and a leg of the Y-fitting (European Offenlegungsschrift No. 00 09 543), the same problems as noted above arise.